1. Field of the Invention
The present invention relates to a black dye composition and a black ink composition suitable for paper ink-jet printing.
2. Description of the Related Prior Art
Ink-jet printing is a non-impact printing method, and the involved features thereof include sharp, non-feathering patterns, good water-fastness, light-fastness, and optical density. Properties such as fast drying and fine storage stability, fine fluency of ink, and non-clogging are also included.
As reactive dyes (such as C.I. Reactive Black 31) are used as the components of ink-jet printing ink, with time the reactive groups undergo hydrolysis, which then results in instability of pH value and an increasing amount of salts in the ink, and the issues of clogging at the nozzles or variability of the hue of the ink and others occur.
U.S. Pat. No. 4,694,302 and U.S. Pat. No. 5,062,892 disclose that the dyes (such as C.I. Food Black 2) commonly used as the components of black ink in the past exhibit poor light-fastness and other properties.
U.S. Publication No. 2007/0050926 and U.S. Publication No. 2006/0174800 disclose that a dye mixture used for preparing a black ink composition can improve the light-fastness, but the light-fastness and the color strength still cannot satisfy the above requirements for printing.
As a result, the effort for a dye composition for the ink-jet printing ink with good light-fastness, high color strength, good solubility and fine fluency of ink is a direction to keep working.